The End (1) - S6-E17
Trivia: The Oceanic employee delivering Jack's father's body has a name visible on his navy blue overall - it is Bocklin - Arnold Bocklin is an artist famous for painting "Isle of the Dead" in 1880. (00:04:00)
Trivia: In series 2, episode 2, at around the 35 minute mark when the camera goes underwater to show the shark swimming past, the shark has the Dharma logo on the back end of it.
Trivia: Terry O'Quinn is the only actor who didn't have to audition for the show, having previously worked with J.J. Abrams on "Alias."
Trivia: Sawyer was not originally Southern - Damon Lindelof described the original character plan as a 'slick, city con man.' It was changed specifically for Josh Holloway.
Trivia: In the first flashback of Kate, when she jumps into Kevin's arms, Evangeline Lilly was so enthusiastically into the scene that during one take, she accidentally knocked Nathan Fillion into the hallway wall behind him.
Born to Run - S1-E22
Trivia: When Kate runs out of the MRI room, if you look closely at the sign, instead of saying "Magnetic Resonance Imaging" as it should, it says "Magnetic Resonance ImagINing". A clue, perhaps? Too big to be an unnoticed mistake.
Man of Science, Man of Faith - S2-E1
Trivia: During the opening scene, when the camera cuts to the cabinet of drugs (shortly before the explosion heard in the distance), all the bottles of drugs have 'the numbers' on them - '4, 8, 15, 16, 23, 42'. Maybe obvious to some but worth looking out for.
Trivia: In the midst of withdrawal, the third time Charlie asks Locke for his stash Locke finally hands it to Charlie, who stares at the bag of heroin. On the DVD commentary, Dom Monaghan remarks that while he holds the bag of heroin (really brown sugar, but hey) he's "doing a Gollum" - using Andy Serkis's portrayal of Gollum, and his desire for his "Precious" as the basis for Charlie's intense need for the drug.
Trivia: Evangeline Lilly almost wasn't cast as Kate. As a Canadian citizen, problems arose regarding her visa and Screen Actors' Guild paperwork. She managed to get everything in order the day before the pilot began shooting.
Trivia: Jorge Garcia (Hurley) missed his sister's wedding to film the show.
Trivia: Swoozie Kurtz plays Terry O'Quinn's mother in the series, even though in real life she's only six years older than him.
Trivia: As Hurley runs to catch the doomed flight, he runs past a girl's soccer team. The numbers on their backs are 4, 8, 15, 16, 23 and 42 - the same numbers that Hurley used to win the lottery, that are printed on the side of the hatch and that were broadcasted from the island itself.
Homecoming - S1-E15
Trivia: When Charlie meets the wealthy lady in his flashback scenes, she mentions that her father is buying a paper company up in Slough, an obvious reference to the UK version of "The Office" which is about a paper company in Slough.
Chosen answer: None of the main characters died in the plane crash. Many died on the island after the crash (Jack, Charlie, Sun, Jin, Daniel, Juliet, others), some lived on the island for an apparently long time after the crash (Hurley, Ben, Bernard, Rose) but some lived lives off the island after the crash (Sawyer, Kate, Claire, Miles, Aplert, and Lapidus). Remember that Christian tells Jack that "time has no meaning here," (in Purgatory). When everyone meets at the church, they are at the end of their lives however long that may have been and will now "move on" together. They look like they did on the island because that is the way they best remember each other.
That has to be the clearest explanation of the ending I've ever read.